Study on micro bubbles started around 1985 . Micro bubbles belong to a new technological field, and have a large number of features to be revealed. Currently, the following three phenomena of micro bubbles are known.
One phenomenon is that each micro bubble, which has a small size, enters deep inside, for example, a web of fibers or a pore, and pushes out any clogging dirt.
The second phenomenon is that, when discharged into water, micro bubbles are pressed under water pressure to become further smaller nano bubbles. Micro bubbles in liquid disappear or turn into nano bubbles in 30 to 60 seconds approximately. Having turned into nano bubbles, the bubbles stay in the liquid for several hours to several days.
The third phenomenon is pressurized breakdown. Pressurized breakdown is a phenomenon that, when discharged into water, a micro bubble is pressed down under water pressure and turned into a nano bubble smaller than the micro bubble, and eventually, the nano bubble has an internal air pressure of 300 atm approximately and breaks down. It is thought that, before this pressurized breakdown, ultrasonic at 400 kilometers per hour approximately, and heat at high temperature near 5500° C. are generated. Then, it is thought that a synergistic effect of these three phenomena allows easy removal of, for example, dirt.
Six known schemes for generating micro bubbles include, for example, a fast shearing scheme, a pressurized breakdown scheme, and a cavitation scheme. Most of the schemes suck external air using, for example, an aspirator, or perform forced injection thereof.
Patent Literature 1 discloses a shower head not including a water spray plate. Patent Literature 1, which is a patent application by the inventor, is a water discharging port unit that can achieve water discharge in a spray form to provide a desirable shower feeling without a water spray plate and can be attached to an end of a shower hose. A flow speed is increased through a narrowed water passage according to a principle of a rubber hose. Before this, a member for causing flowing water to generate swirling flow is incorporated at an entrance of the water passage to increase the flow speed. Then, the flow speed is further increased through a narrowed part of the water passage, which gradually decreases in size to twist the water flow. This flowing water is abruptly discharged in a spray form at the water discharging port unit. In this manner, the disclosed shower water discharging port can provide a desirable shower feeling without a water spray plate.
Patent Literature 1 discloses the structure including no water spray plate but has no description of micro bubbles. The disclosure is a simple tubular object including a first component and a second component connected with a leading end of a hose, but not having the shape of a typical shower head, which makes it difficult to hold the tubular object as a shower head. Thus, the tubular object can cause injury by hitting the head of a user, or can be damaged by dropping, for example.